1. Field of the Invention
The invention relates to an information signal recording and reproducing apparatus and a recording and reproducing method, in which a recording medium is effectively used when a main signal such as video and audio signals is recorded into the recording medium.
2. Description of the Related Art
When analog data or digital data is recorded to a recording medium such as magnetic tape, magnetic disk, optical disk, or the like, there is a case where a vacant region necessary to newly record data to the recording medium does not exist. In such a case, although it is sufficient to use a new recording medium such as a blank disk, an amount of recording media increases without any restriction.
To avoid such a problem, it is considered to erase the unnecessary signals among the recorded signals. For example, in an automatic recording apparatus such as a monitor video camera having a VTR, an endless tape is used and when the signal is recorded to the end of the tape, a recording position is returned to the start of the tape and an image signal is newly recorded. It is also considered to similarly record digital data by using a ring buffer in place of the endless tape. Further, there has also been proposed a method whereby when image data is recorded onto the optical disk, new and old information is recorded onto the optical disk together with the image data and, when a recording capacity remaining in the optical disk is equal to 0, the oldest data is erased. Moreover, a method of erasing the data after the elapse of a predetermined time from the recording time has also been proposed.
However, in the data which has already recorded in the recording medium, it is improper to determine whether the data is unnecessary or not by only checking whether the data is new or old. This is because the duration of a period of time during which the user wants to preserve is influenced by the contents of the recorded signal. For instance, in a VTR for recording a television broadcasting program, among the programs, in case of programs such as news, weather forecast, or the like in which instantaneousness is required, it is sufficient that the preserving period is short. On the other hand, in case of a movie program, it is required that it is preserved for a longer period of time. In accordance with the user, there is also a case where he wants to set a preserving period on the basis of a broadcasting channel, the title of the program, and the like.